So, I've been trying to figure out what this movie is actually about. One theory I've had is that it's about white male mediocrity. Pippin himself bemoans his less than "extraordinary" existence and how he wants to do more, but he, by his own admission, kind of sucks at all of it. Ultimately, The Lead Player tells him that the best thing he can do is die in a spectacular fashion -- and he ends up fucking that up too.
At least, that's what I got out of it.
Of course there was a line cut from the performance. At the end, when asked how he's feeling, Pippin is supposed to reply, "Trapped, which isn't bad for a Musical Comedy." Fosse wanted that line to be "Trapped, but happy, which isn't bad for a Musical Comedy." Honestly, I like how this performance ended as it leaves his response ambiguous. However, I also like Fosse's rewrite since, if I'm right about white male mediocrity, it ends with him dissatisfied, but accepting his limitations.